The permanent joining or bonding of structure wafers takes place preferably by diffusion bonds, eutectic bonds or glass frit bonds, Cu—Cu combinations in recent years being especially preferred for many applications.
High temperatures and/or pressures for a stable irreversible bond are necessary for the joining.
In structure wafers which are becoming thinner and thinner in diameter and larger and larger in area, major difficulties always arise for bonding methods, especially since the yield of chips is to be as large as possible. On the other hand, there is the requirement of economical and careful production of a permanent bond on the joining surface or contact surface between the wafers.